2-methyl-3-methylene-1,5,7-octatriene,its oligometer,and its preparation from allene and butadiene with palladium(o) catalysts

ABSTRACT

The tetraene 2-methyl-3-methylene-1,5,7-octatriene in both cis and trans forms is obtained by liquid-phase reaction between allene and butadiene in the presence of a Pd(O) complex catalyst. The tetraene readily forms an oligomer useful as a vehicle in air-dried finishes.

United States Patent Coulson [4 1 Sept. 12, 1972 [54] 2-METHYL-3-METHYLENE-1,5,7- 3,444,258 5/1969 Kohnle et al. ..260/677 OCTATRIENE, ITS OLIGOMETER, 3,522,321 7/1970 De Young ..260/666 B AND ITS PREPARATION FROM ALLENE AND BUTADIENE WITH PALLADIUM(O) CATALYSTS Dale Robert Coulson, Wilmington, Del.

Assignee: E. l. du Pont de Nemours and Company, Wilmington, Del.

Filed: March 9, 1971 Appl. No.2 122,537

Inventor:

References Cited UNITED STATES PATENTS 6/1967 Gebura ..260/677 Primary Examiner-Delbert E. Gantz Assistant Examiner-J. Nelson Attorney-James B. Ryan [5 7] ABSTRACT The tetraene 2-methyl-3-methylene-l ,5,7-octatriene in both cis and trans forms is obtained by liquid-phase reaction between allene and butadiene in the presence of a Pd(0) complex catalyst. The tetraene readily forms an oligomer useful as a vehicle in air-dried finishes.

5 Claims, No Drawings 2-METHYL-3-METHYLENE- 1 ,5 ,7-OCTATRIENE, ITS OLIGOMETER, AND ITS PREPARATION FROM ALLENE AND BUTADIENE WITH PALLADIUM(O) CATALYSTS BACKGROUND OF THE INVENTION 1 Field of the Invention This invention relates to, and has as objects provil sions of, the reaction of allene with butadiene in the presence of a palladium(0) complex catalyst and the tetraene product, cisand trans-2-methyl-3-methylene- 1,5,7-octatriene, obtained thereby. Oligomers of the tetraene are alsoprovided.

2. Prior Art No prior disclosure is known of the subject product and process. Certain compounds related to 2-methyl-3- methylene-l,5,7-octatriene and their preparation by processes different from the present are described in the literature, e.g.;

a. Butler and Raymond, J. Macromol. Chem. 1, 201 (1966), describes polymerization with a Zieglertype catalyst system of certain tetraenes, including 3,6-dimethylene-l,7e-octadiene. The polymers are said to have a cyclic-type structure.

b. Butler and Raymond, J. Org. Chem. 30, 2410 CH2 CH2 CH2 CH in which each R, independently, is a one to 20 carbon alkyl (sic) radical and each R independently, is a one to four carbon alkyl radical.

e. Stille and Plummer, J. Org. Chem. 26, 4026 (1961), discusses, and contains additional references to, polymerization of tetraenes by the Diels-Alder reaction. Polymeri zations of certain biscyclopentadienes are specifically described.

DESCRIPTION AND DETAILS OF THE INVENTION In the present invention, cis and trans-2-methyl-3- methylene-I,5,7-octatriene is prepared according to the equation:

The reaction is carried out by mixing the reactants and catalyst under liquid phase conditions.

The process can be operated at temperatures in the range of about C. to about C., and pressure is not critical except as necessary to keep the reactants in the liquid phase. Pressures up to about 500 psig are considered sufficient, though higher pressures could be used if desired.

As is evident from the equation above, the present reaction takes place with a stoichiometrical allenezbutadiene molar ratio of 2:1. Formation of the tetraene apparently is favored by low allene:butadiene mole ratios. The process is operable with allenezbutadiene mole ratios in the range of about 1:10 to about 10:l, ratios in the range of about 1:3 to 2:1 being preferred.

The palladium(0) complex catalysts necessary for the invention are apparently unique, since other palladium catalysts, including the free metal, have been found inoperable. Any paIladium(O) complex is regarded as suitable in the reaction. Several can, of course, be used simultaneously but to no advantage. The catalysts of the examples given below are bis(triphenylphosphine)(maleic anhydride)palladium(O) and tetrakis(triphenylphosphine)palladium( 0). Representative operable equivalents are listed in the Table which follows.

TABLE Name Formula Ref) 1 'Ietrakis(triphenylphosphine)palladium(0) Pd[(C6H5) P]i Bis(triphenylphosphine)-(maleic anhydride)pal1adium(0) Pd[(CaH5)3P]2 %O 2 /0 H C-C Bis(triphenylphosphine)-(dimethyl fumaratn)palladiurn(0). Pd[(CsII5)3I]z g) 2 0 H3O C-CII ll H -COCHa I)is(triphcnylphosphine)-(dimethyl inaleate)palladiuni(O) Pd[(CuH5)aP]2 H) 2 H C O C H3 ii i II 0-0 0 0 Ha Bis]1,2-bis(dimcthylphosphino)-ethane]palladium(0).. Pd[(CHmPOHQCHQHCHQMZ 3 TABLE Continued Name Formula Ref. 1

lush-bis( 1iethylphosphino)-benzene]pa1ladium(0) Pd 4 3 W 2115): -P (C2115):

Bis[bis(diphenylphosphino)methane]palladium(0) ldlLCGlIs):lClhlWlrllm]: 3

[iis[1,2 bis(diphenylphosphino)-etlmue]pallodium() Pd[(CsII5):ICII2CI[:IUhil 1.021; 21

Bis[0-bis(dimethylarsino)-benzene]palladium(O) Pd :1

;\5(("Il;l)2

AS(GII.1)2

References:

l. Malatesta et al., J. Chem. Soc., 1957, 1186. 2. Takahashi, et al., Nippon Kagaku. Zasshi 88, 1306 (1967). 3. Chatt et al., J. Chem. Soc. 1962, 2537.

Palladium(0) catalysts which promote the formation of 2-methyl-3-methylene-1,5,7-octatriene from allene and butadiene can also promote side reactions, e.g., linear dimerization of butadiene to 1,3,7-octatriene [Takahashi et al., Bull Chem. Soc. (Japan) 41, 454 (1968); Chem. Abs. 69, 35305e (1968)]. Such side reactions might involve conversion of primary tetraene product to unknown secondary products. Accordingly, optimum production of 2-methyl-3-methylene-l,5,7- octatriene in the process is a very complex question but has not been explored. In view of evidence that the presence of a relatively high molar proportion of the catalyst can result in a product containing no identifiable 2-methyl-3-methylene-l,5,7-octatriene, it is considered impractical to use catalyst in a molar ratio of catalyst:allene-plus-butadiene greater than about 1:200, i.e., a catalytic amount. The preferred catalyst:allene-plus-butadiene molar ratios are in the range of about 1:500 to about 1:5,000.

The 2-methyl-3-methylene-l ,5 ,7-octatriene product of the invention comprises a mixture of the cis and trans stereoisomers, which can be thermally oligomerized to an essentially nonvolatile viscous liquid oligomer. The oligomer, also a product of the invention, is a polyunsaturated oil which is useful as a vehicle in air-dried finishes, such as a clear varnish or a pigmented oil paint for protecting or decorating wood surfaces.

EMBODIMENTS OF THE INVENTION The process of preparing 2-methyl-3-methylene- 1,5,7-octatriene from allene and butadiene, thermal oligomerization of the tetraene, and use of the oligomer in air-drying varnishes are described in the following examples. In these examples, temperatures are in degrees Centigrade and percentages are by weight.

EXAMPLE 1 2-Methyl-3-methylene-l ,5 ,7-octatriene A solution of 1.47 g (2 mmole) of bis(triphenylphosphine)(maleic anhydride)palladium(O) in 100 ml of tetrahydrofuran was charged to a 400 ml stainless steellined autoclave. The closed system was cooled and evacuated to mm pressure. To this was then added 20 g (500 mmole) of allene and 108 g (2,000 mmole) of butadiene. The autoclave was heated to 120 for 6 hours. The resulting clear yellow-red solution was distilled directly giving 8.31 g (24 percent yield, based on allene charged) of a 2:1 mixture of transand cis-2-methyl-3-methylene-l ,5 ,7-octatriene, b.p. 5556.5/7.8 mm. Anal. Calcd. for CWHH: C, 89.50; H, 10.51

Found: C, 89.60; H, 10.60 Nmr (220 MHz, CCl,): 6 1.88 ppm (s, H); 2.97 (d,j= 71-12, H, H", trans-isomers); 3.08 (d, j 7H2, H, H", cis-isomer); 4.82-5.20 (m, H, H", H", H, H, H"); 5.40-6.65 (m, H, H, H,j 9 Hz,j 14 Hz).

cis trans H H i i CH3 II He H 11 l Hi In Infrared (neat): 1,595 cm", 1,630 cm and 1,650 cm Ultraviolet (EtOH): A 225 M/L, e= 35,600

The identity of 2-methyl-3-methylene-l,5,7octatriene obtained by the process of Example 1 was confirmed by the following experiment:

A mixture of cisand trans-2-methyl-3-methylene- 1,5,7-octatriene (1.34 g, 97 percent purity) and 5 percent palladium on carbon (0.1 g) of ethanol (10 ml) was exposed to a hydrogen atmosphere with stirring. The mixture absorbed a total of 944 ml of hydrogen. This corresponds to 3.90 double bond equivalents. The mixture was filtered and evaporated of ethanol giving a colorless liquid. Purification of the major component (87 percent) by gas-liquid chromatography gave a liquid whose infrared spectrum was identical to that of known 2,3-dimethyloctane.

A gas chromatographic analysis procedure for 2- methyl-3-methylene-l,5,7-octatriene in crude reaction mixtures obtained by the process of Example 1 was established as follows:

A solution of allene, butadiene, and bis(triphenylphosphine)(maleic anhydride)palladium(0) in 25 ml of tetrahydrofuran was heated to 120 for 6 hours in an ml stainless steel-lined bomb. The resulting solution was analyzed by gas-liquid chromatography and compared with a standard solution of distilled 2-methyl-3- methylene-l,5,7-octatriene in tetrahydrofuran. The analysis conditions found most suitable involved a 20 percent silicon gum nitrile column material on 60-80 mesh Chromosorb W. The column was 8 feet X V4 of an inch in dimensions and the temperature used was 80.

EXAMPLES 2-9 The effect of mole ratio of reactants on yield of 2- methyl 3-methylene-l ,5,7-octatriene(l) is illustrated in 5 6 the results of a series of runs with allene, butadiene and yield, and that isolation of the product is difficult. The bis(triphenylphosphine)(maleic anhydride)palladiprincipal impurity is a linear dimer of butadiene, 1,3,7-

um(O) catalyst in 25 m1 of tetrahydrofuran heated to octatriene. 120 for 6 hours in an 80 ml stainless steel-lined bomb. The data for these examples are presented in Table 2. 5 EXAMPLE l5 The yield data are based on gas chromatographic 2 Methyl 3 methylene l 5 lactatriene analyses of the crude reaction products.

A solution of tetrakis(triphenylphosphine)palladi- TABLEz um() (1.16 g, l mmole) in 20 ml tetrahydrofuran was mmole mmole mmole 10 charged to an 80 ml stainless steel-lined autoclave. Bu-

of of of Yield tadiene (32.4 g, 600 mmoles) and allene (4 g, 100

' I Example Allene Butadene Camus mmoles) were also charged to the vessel under pressure. The autoclave was then heated to 120 for 5 hrs.

5 328 23 ii l 5 The resulting solution was analyzed by gas-liquid chro- 4 250 250 0.5 32 matography for the presence of cisand trans-2- g; g methyl-3-methylene-l,5,7-octatriene. The analysis in- 7 125 375 33 dicated a yield of 1.7 percent, based on the amount of 8 125 375 -5 47 allene charged. 9 125 375 1.0 11

EXAMPLE 16 Based on the amount of allene charged. oligomerizationof y y ,5 r

octatriene EXAMPLES -13 25 A. A solution of cisand 'trans-2-methyl-3- The effect of different solvents on yield of 2-methylmethylene-1,5,7 ctatriene (4 d h d i 3-methylene-l,5,7-octatriene(l) is illustrated in the one (0,01 in benzene (20 ml) was heated to data presented in Table 3. Each reaction mixture con- 190 f 5 hr Th resulting solution was mined g mmQle) 0f butadiene, 4 evaporated to dryness at 0.2" mm pressure. The mmole) 0f a11ene,0-18 g( mm01e)0fb1S(Il'1Phen' residue weighed 2.57 g and was clear viscous ylphosphine)(maleic anhydride)palladium(0) catalyst 1i id and 25 ml of solvent. Each mixture was contained in an Nmr analysis f material revealed an aliphatic 80 ml stainless steellined bomb and was heated to 120 protomolefinic proton ratio of Propagation of a for 5 hours. The yields are based on gas chromatochain by any Single bond of 2 methyl 3 methylene graphic analyses of the crude reaction products. 1,57octatriehe would have given this ratio a TABLE 3 imum value of 1.33. Also, the ratio of terminal olefinic protons to internal olefinic protons was found to be 0.8. Example Solve!" Yield of In the parent monomer this latter ratio is 2.0. Thus, the

involvement of terminal methylenes in the oligomerizal0 Acetonitrile 6.8 tion is suggested. All of this evidence is consistent with i; gf I a Diels-Alder oligomerization as follows:

oroform 0 a 13 Benzene 35.0 II C a A I Based on the amount of allene charged. 4 CH3 H EXAMPLE 14 2-Methyl-3-methylene-1 ,5,7-octatriene H and/0r A solution of 1.47 g (2 mmoles) of bis(triphenl J ylphosphine)(maleic anhydride)palladium(0) in 25 ml k n k Of tetrahydrofuran was charged t0 a 400 ml stainless The value of n in the oligomer (a low-molecular steel-lined autoclave. The closed system was cooled to weight homopolymer) is probably between 2 and 3 as approximately 50 and evacuated to approxima ely judged by the molecular weight of 329 found by cryo- 20 mm pressure. To this system was then added 162 g scopic measurements in benzene.

(3,000 mmole) of butadiene and 20 g (500 mmole) of B. A sample of the above oligomer was spread out on allene. The autoclave was heated to l20 for 5 hours. a microscope slide and allowed to stand. After 3 The resulting solution was analyzed by gas-liquid chrodays at room temperature a clear, colorless hard matography. An 8i percent yield of a mixture of ciscoating resulted. and trans-2-methyl-3-methylencl ,5,7-octatrienc, I, C. A solution of L4 g of the oligomer and 0.10 ml of was found. Distillation on an 18 inch spinning band Noudex (a commercial drying agent containing column afforded 13.0 g (39 percent yield, based on alcobalt naphthenate [6 percent cobalt content] in a lene) of l. The recovered yield of l was low because of hydrocarbon vehicle, prepared by Tenneco the difficulty in separation from impurities. Chemicals, Inc., Noudex Div.) in 4 ml of benzene This example illustrates that the process of Example was prepared. This solution was applied with a l is capable of producing the tetraene product in high brush to a 4 X 6 inch glass plate and a white pine surface (12 X 2 inch), respectively. After standing for 2% hours at room temperature, hard clear coatings adhered strongly to both surfaces. Further standing enhanced the hardness.

Since obvious modifications and equivalents will be evident to those skilled in the chemical arts, I propose to be bound by the following claims.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

l. 2-Methyl-3-methylene-l ,5,7-octatriene.

2. The process of preparing the compound of claim 1 which comprises reacting allene with butadiene in liquid phase and in the presence of a catalyst of a palladium(0) complex the said palladium (0) complex catalyst having a catalyst to allene and butadiene molar ratio of about 1:200 to about 1:5,000.

3. The process of claim 2 employing an inert diluent.

4. The process of claim 2 wherein the complex is bis(triphenylphosphine)(maleic anhydride)palladium(0).

5. The process of claim 2 wherein the complex is tetrakis(triphenylphosphine)palladium(O). 

2. The process of preparing the compound of claim 1 which comprises reacting allene with butadiene in liquid phase and in the presence of a catalyst of a palladium(O) complex the said palladium (O) complex catalyst having a catalyst to allene and butadiene molar ratio of about 1:200 to about 1:5,000.
 3. The process of claim 2 employing an inert diluent.
 4. The process of claim 2 wherein the complex is bis(triphenylphosphine)(maleic anhydride)palladium(O).
 5. The process of claim 2 wherein the complex is tetrakis(triphenylphosphine)palladium(O). 